Treasure Chest (DN)  

Dragon Nest Wikibase™ Dictionary

In all Dungeons there will be at least one Treasure Chest, usually hidden somewhere behind some boxes, barrels or a wooden barricade. Sometimes you must open a door to reach the chest and it may not be obvious. Treasure Chests come in wood, metal and Royal. Metal chests tend to have more coin (like silver) and better items. Move your target reticule over the lock to get the Key icon, then click to open the chest, then pick up the contents.

Very rarely you may find a Royal Treasure Chest which will have a lot more coin of higher value (gold!) and magic, rare or epic items. This does not replace the regular treasure chests for the dungeon and usually, but not always, appears right next to one.

Wooden and Metal Treasure Chests	Royal Treasure Chest